Ability to remove public bodies from search index

[garethrees]

On the WhatDoTheyKnow Community & Activism call last night we discussed wanting to have the ability to remove a group of authorities from the internal search index.

We could do this one of two ways.

1. By adding a noindex special tag
2. By adding Prominencable with a backpage option

Using a noindex tag would likely be marginally quicker to implement – basically:

  acts_as_xapian texts: [:name, :short_name, :notes_as_string],
  # …
+ if: :indexed_by_search?

+ def indexed_by_search?
+   !tagged?('noindex')
+ end

Adding Prominencable might be a little extra work, but have some additional benefits.

It would be more consistent with other similar record types and better integrate with the “eye” icon around the admin interface, and we could later add the hidden state which would allow us to draft forthcoming authorities (#7298) without them being visible.

Another benefit, especially for the group of authorities we discussed, is that backpage also prevents external indexing. Looks like we have an easy mechanism to apply this via ProminenceHeaders.